Eastern North Pacific Tropical Weather Discussion (Text)

000
AXPZ20 KNHC 190936
TWDEP
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Mon Mar 19 2018
Tropical Weather Discussion for the eastern Pacific Ocean from
the Equator to 32N, east of 140W. The following information is
based on satellite imagery, weather observations, radar, and
meteorological analysis.
Based on 0600 UTC surface analysis and satellite imagery through
0915 UTC.
...SPECIAL FEATURES...
Gale Warning: A weakening cold front over the far northwest
portion of the area along a position from 32N137W to 26N140W is
preceded by strong southerly flow north of 25N and within 420 nm
to its east, along with seas of 8 to 10 ft. A deepening surface
low pres system currently northwest of the area at 36N143W will
drop southeastward to near 32N140W on Mon night behind this
initial cold front, and drag a second cold front into the
discussion area accompanied by a strong to near gale southwest-
west-northwest wind shift. The pressure gradient will tighten
around the southwest semicircle of the low increasing the
westerly winds to minimal gale force winds in the range of
30 to 35 kt over the discussion waters from 29N to 30N west of
139W near 0900 UTC on Tue, with the associated seas of 14 to 19
ft forecast from 26N to 32N between 136W and 140W. The low pres
will lift north of the area on Tue afternoon, with associated
winds diminishing to 20 kt or less south of 32N on Wed evening.
The associated NW swell, in the form of 7 to 10 ft seas, will
propagate southeastward through the waters covering the area west
of a line from the Central Baja peninsula to 06N140W on Sat.
Please refer to the Pacific high seas forecast for more details
on this upcoming event under AWIPS/WMO headers MIAHSFEP2/FZPN03
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
A surface trough axis is analyzed from low pres over NW Colombia
westward to across northern Panama and to just offshore the
border between Costa Rica and Panama continuing to 06N90W to
06N97W, where latest scatterometer winds indicate the ITCZ axis
begins and continues to 06N110W to 07N125W and to beyond
07N140W. Scattered moderate isolated strong convection is noted
within 180 nm S of the axis between 86W and 88W, also within
60 nm N of the axis between 115W and 118W and within 30 nm of the
axis between 118W and 122W.
...DISCUSSION...
OFFSHORE WATERS WITHIN 250 NM OF MEXICO...
A north-northwest to south-southeast ridge extending from
30N121W to 17N110W to 13N94W will shift slightly to the
southwest through Tue. Fresh to locally strong northerly winds
will set up south of 25N and east of the ridge briefly on Mon and
Mon night with the pressure gradient then relaxing some on Tue.
Light to gentle northerly winds and 3 to 4 ft seas are then
expected west of the Baja Peninsula through Wed. Broken to
scattered mid and high level clouds are advecting eastward
towards northern and central Baja California north of 26N as
well as to the northeast in the direction of southern
California.
Gulf of California: Moderate to fresh northwest flow is forecast
across the entire gulf waters today, with narrow swaths of
strong northwest winds expected across the far southern gulf
waters late Mon. Seas may build to 6 ft in the longer fetch
waters.
Fresh to locally strong northwest to north flow expected across
the open Pacific waters from 18N to 23N east of 110W through
late tonight with seas building to 8 ft.
Gulf of Tehuantepec: Strong north flow will surge through the
gulf waters on Tue evening, increasing to minimal gale force
Wed evening. Gale conditions are then expected to continue
through Thu morning, with seas building to a maximum of around
14 ft downstream from the gulf near 14.5N95.5W on Wed night.
OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND
WITHIN 750 NM OF ECUADOR...
Gulf of Papagayo: Fresh to locally strong NE nocturnal winds
will diminish to moderate winds this afternoon, then increase to
strong winds again briefly on Tue night with seas building to 7
ft downstream. A stronger drainage event is forecast to begin on
Wed night, and persist into the upcoming weekend.
Gulf of Panama: Fresh northerly winds will diminish to moderate
winds this afternoon. Fresh to strong north nocturnal winds are
expected to resume on Wed night.
Elsewhere, gentle to moderate offshore flow will prevail N of
07N while light to gentle SW winds are forecast S of 07N.
REMAINDER OF THE AREA...
Please see see Special Features Section above for details on
upcoming gale force winds to impact the far NW portion of the
area in the short-term.
A very progressive pattern will continue to impact the the
northwest portion of the area well into this week. The deep
layer low pres system located to the northwest of the area and
its related trough is preceded by mid to upper level moisture in
the form of overcast cloudiness. Areas of rain along with
scattered showers and isolated thunderstorms under upper level
divergence that is present to the the east and southeast of this
low have moved over the area north of about 27N and west of 120W.
These clouds and precipitation will continue advancing eastward
towards the general area of southern California and also northern
and central Baja California through Wed per model moisture
guidance fields.
$$
Aguirre